1. Field of the Invention
The invention relates to a floor covering. Particularly, the invention relates to a floor covering wear layer and seam coater, and more particularly to a floor covering having a urethane component which has a glass transition temperature or T.sub.g of at least about 40.degree. C. The urethane component may be a wear layer or seam coater, or both.
2. Background of the Invention
Floor coverings including resilient floor coverings are well known in the art. The floor coverings which are in wide use today are primarily of vinyl construction and, although they can be constructed to have varying degrees of flexibility, they are "resilient" when compared to conventional natural materials, such as ceramic tile. The term "resilient" describes the characteristic of a floor covering to recover from the indentation made by a heavy object such as a refrigerator.
A variety of such products are commercially available and these products have proven to exhibit good wear resistance. However, such coverings are not without certain deficiencies. For example, although vinyl flooring products are durable and stain resistant, they nevertheless tend to lose their glossy appearance through wear. A high-gloss appearance for a floor covering is often desired. Accordingly, the manufacturers of such materials have long sought to find improved floor coverings which exhibit good gloss retention.
One method of providing improved gloss retention is through the application of polyurethane or other wear layers to vinyl flooring structures. Nevertheless, these wear layers, and in particular polyurethane wear layers, also have certain drawbacks. For example, they are more susceptible to staining. Thus, when exposed to common household stains as ballpoint pen, lipstick, mustard, shoe polish and the like, polyurethane coatings tend to be more easily stained than vinyl coatings.
This staining problem has at least been diminished by using polyurethane thinly covered by other more highly crosslinked wear layers, including a coating formed by thermally curing a surface covering composition of an aminoplast component, a polyol component, an acid catalyst component, and an optional vinyl resin component. Such wear layers are disclosed in Bolgiano et al. U.S. Pat. No. 4,781,987 and Witman U.S. Pat. No. 4,935,286, for example.
Because of the crosslinking and few chemically reactive sites on the surface of such wear layers, it has been difficult to find compositions which adhere to the surfaces and which have good enough stain and wear resistance to be used as seam coaters to prevent the buildup of dirt and penetration of moisture between the seams of surface coverings, particularly floor coverings, having such wear layers. The wear layer composition itself cannot be practically used as a seam coater or sealer since it is thermally cured. One solution has been to use a cyanoacrylate based composition. However, the cyanoacrylate composition releases objectionable fumes.
Additional polyurethane surface coatings are disclosed in Conger et al. U.S. Pat. No. 4, 059,709, Haemer et al. U.S. Pat. No. 4,298,646 and Boba et al. U.S. Pat. No. 4,393,187. The polyurethane/urea compositions of the prior art which are used as wear layers have a low T.sub.g. That is, they have glass transition temperatures in the range of about 18.degree. C. to about 23.degree. C.
One objective of the present invention is to provide a seam coating composition which can be used with the polyurethane wear layers and the aminoplast wear layers of the prior art.
Another objective of the present invention is to provide a composition which can be used as the wear layer composition itself as well as the seam coater.
Further object of the present invention is to provide a wear layer composition which has good stain resistance, gloss retention under foot traffic, alkali resistance and reasonable curing time.
These and other advantages of the present invention will become apparent from the detailed description of the preferred embodiments which follow.